Effect of cut twisted tape and Al2O3 nanofluid on heat transfer of double tube heat exchanger

Transcription

1 mme.modares.ac.ir 4 3 * a.tavakoli@sut.ac.ir * 3.. / /5/ : : : EffectofcuttwistedtapeandAl2O3nanofluidonheattransferofdouble tubeheatexchanger SamiraKhanjani AkramTavakoli * DavoodJalaliVahid 2 MeysamNazari -DepartmentofChemicalEngineering,SahandUniversityofTechnology,Tabriz,Iran 2-DepartmentofMechanicalEngineering,SahandUniversityofTechnology,Tabriz,Iran *P.O.B Tabriz,Iran,a.tavakoli@sut.ac.ir ARTICLEINFORMATION ABSTRACT OriginalsearchPaper ceived24june25 Accepted3September25 AvailableOnline28October25 Keywords: Nanofluid Doublepipeheatexchanger Cuttwistedtape Convectiveheattransfer In this study, forced convective heat transfer characteristics ofal O /water nanofluid flowing through double pipe heat exchanger with plain twisted tape and cut twisted tape inserts are investigatedexperimentallytorevealtheeffectofcuttwistedtapeandnanofluidconcentrationon heat transfer. Experiments are conducted in turbulent flow regime with number ranging from -3andintheparticlevolumeconcentrationrangeof<<.%.Theresultsof thermal studies showed enhancement of convective heat transfer with Al O nanofluids comparedwithflowofwater.also,itwasfoundthatinhigherynoldsnumbersthenanofluid hasbetterheattransfercapability.theeffectsoftwistedtapewithandwithoutcutsonedgeson heattransfercoefficientandratewereinvestigated.itwasfoundthatthetwistedtapewithcut edgescouldenhanceheattransferratebetterthantwistedtapewithoutcutedges.thepressure dropwasinvestigatedforflowofnanofluidandwater.theresultsshowedthatthereisthereis littledifferencebetweenpressuredropsinthesecases.frictionfactorandpressuredropintube with plain twisted tape and cut twisted tape inserts are increased due to increasing flow resistanceandcontactsurfacebetweenfluidandflowpassage...[]. -. Pleasecitethisarticleusing: : S. Khanjani, A. Tavakoli, D. Jalali Vahid, M. Nazari, Effect of cut twisted tape and Al2O3 nanoluid on heat transfer of double tube heat exchanger, Modares Mechanical Engineering Vol.5,No.,pp.8-9,25(InPersian)

2 ....[8] TiO / [3]. %/2 -. % [9]. Al O..[]. Fe O.[]. 6 [2] % /6 % 8/49 % 3/96 5. [3] /3/5 Al O. [4] 42/75 v. [5] [6]. /2 /2 TiO /.. [7] [2] [3] [4].... [5] [6]. % %/3 [7]

3 .. ) ) ) (.. ( ( 2 ( =,, () - 2. U /5 35 /9 4 (TT. 3 2 (CTT) U 5 ). ( -7 C.. / /5/25. LM TwistedTape 2-CutTwistedTape

4 f,,, u (2) = + ( ), = C, + ( ), C, :[3] (3) (2) (3) (3) (2) (5) (4) = ( + 3) = :[8] (4) (5) [9]. (6) (7) [7] =.23. Pr. = Pe.. Pr. (6) (7) (8). f =.36. = f 2 (8) / =,,,,,, (2) () (2) = (3). %7 %3 (3) (4) = + 2 (4) = (5) (6) =,,,, ln,,,, (5) 7 = (6) (7) (8) = + = =.23R. Pr. 4 < <.6 < Pr < (8) :[4] (9) () (8) = () U ). () - = f 2 ()

5 2 % % o.% 2 2 C 5 C C 7 C 6 [7] 2 4 / (8) [4].. / 3 28/ / _

6 PT TT CTT p / 5/33. 2 (TT) (PT) (CTT) PlainTube 2-TwistedTape 3-CutTwistedTape water % % % water % % %

7 / - 3. [2]... [4].... / 3. 28/ PT TT CTT PT TT CTT p(pa) / p(pa) 2 water % % % 2 wpt wctt.25tt.5pt.5ctt.tt wtt.25pt.25ctt.5tt.pt.ctt

8 = E f E f /3 [22] (9) (9) f /. - /7-/3 / f.35 waterpt watertt waterctt.25%pt.3.25%tt.25%ctt.5%pt.5%tt.5%ctt.%pt.25.%tt.%ctt TT CTT / 6.2 TT. CTT

9 . /. /36 / /6.. / [22]. % 3/22 % 9/ / 3. % 28/ % 42/2 34/ n,ctt - w,p )/ w,p % % %

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